Generic drugmakers will enjoy extensive protections from product liability after a Supreme Court decision Monday made it even harder to sue them in state court.

The 5-4 decision will limit an injured consumer’s ability to bring cases against generic manufacturers, which supply about 80 percent of U.S. prescription drugs. The court noted that federal law requires the generics to be essentially the same as the brand-name counterparts. That means they don’t have control over the wording of labels or the ingredients.

In 2011, the Supreme Court decided in PLIVA v. Mensing that generic drugmakers could not be held accountable in “failure to warn” cases — essentially shortcoming in the labels — because they had no choice in the matter.

The ruling Monday in Mutual Pharmaceutical Co. v. Bartlett builds on that decision, further restricting suits for so-called design defect or drug-safety complaints. Swing Justice Anthony Kennedy joined the four conservative justices.

The attorney for the plaintiff, Karen Bartlett, who suffered rare and devastating side effects from sulindac, argued that generic companies still decide whether to market a drug, even if they can’t control what’s on the label.

A New Hampshire jury found that the medicine was “unreasonably dangerous” and should have been kept off the market. Bartlett, who suffered burns to more than 60 percent of her body, was tube-fed for a year, endured two septic shock episodes and is legally blind, was awarded $21 million in damages.

The Food and Drug Administration reviewed the safety of the class of anti-inflammatory drugs including sulindac after Bartlett’s injuries and required more explicit warnings. It did not pull them from the market.

The Supreme Court ruled that the labeling protections for generic makers in PLIVA applied to the design-defect complaint, as well.

Both the drug company and government lawyers contended that it is up to the FDA’s experts — not lay juries in state courts — to decide the key question of whether a drug’s benefits outweigh its risks and, therefore, whether it should be allowed on the market.

“When it comes to decisions on safety and approval of prescription medicine, the FDA is best equipped to make judgments that affect patients,” Generic Pharmaceutical Association President and CEO Ralph Neas said in a statement. “The experts at FDA alone have the scientific knowledge, regulatory experience and complete data to make these decisions.”

But Rep. Henry Waxman (D-Calif.) and Sen. Tom Harkin (D-Iowa) filed a brief in the case, arguing Congress did not intend for federal law to pre-empt state claims in cases like Bartlett’s, and the four liberal justices dissented in two separate opinions. Justice Stephen Breyer argued that FDA’s opinion shouldn’t give blanket immunity for generic drugmakers in product liability cases.

The restrictions on state lawsuits against generics highlights an issue that consumer advocates are calling a “safety gap”: generic drugs that no longer have brand counterparts on the market are not allowed under federal law to update warnings as they learn of new problems. New risks are sometimes found years after a drug goes on the market — as in the case of the medicine Bartlett took.

Public Citizen published a report coinciding with the ruling Monday that identified 434 generic drugs for which no brand products are sold. The report cites 53 cases in which the FDA required new “black-box warnings” — the most serious kind — for drugs after the generic drug entered the market.

The group is pressing for regulatory changes that would allow generic companies to make labeling changes as risks are discovered. That would change the legal framework because the PLIVA precedent is based on FDA regulation, said Allison Zieve, who petitioned the FDA in 2011 to address the issue. She said she had not received a “substantive response.”

“What the court has said is that generic manufacturers have no responsibility for design or labeling — no responsibility for the safety of their products,” Zieve said. “If FDA gave them responsibility, it would change the legal framework. … In our view, it would lead to fewer injuries because the manufacturers would take responsibility, and it would allow injured patients an avenue to potentially get compensated where appropriate.”

Democrats in the last Congress introduced House and Senate bills that would give generic manufacturers responsibility for updating warnings, Zieve said, but they have not been reintroduced in the current Congress.

After the ruling, Democrats in the House and Senate sent a letter to FDA Commissioner Margaret Hamburg urging her to allow generic drugmakers to update warning labels when new risks are discovered.

Senate Judiciary Committee Chairman Patrick Leahy said in a statement, Monday’s “decision creates a troubling inconsistency in the law that penalizes the millions of Americans who take generic medications. A consumer should not have her rights foreclosed simply because she takes the generic version of a prescription drug.” He had introduced a bill last year to address the labeling issue.